Involvement of endocannabinoid CB1 receptor in the modulation of stress responses related to xenoestrogen exposure.

The endocannabinoid system, through the cannabinoid receptor CB1, is involved in the modulation of adaptive responses to environmental conditions. However, little is known about the role of the cannabinergic system, particularly CB1 receptor expression, in relation to the effects induced by xenoestrogens concerning the reproductive axis. Our results demonstrate that only 10(-8) mol/L of 17beta-estradiol was able to induce significantly higher levels of CB1A mRNA, while no effects were found after treatment with 4-nonylphenol (10(-8) or 10(-6) mol/L); moreover, mRNA expression titers of CB1B did not show any significant change. The estrogenic effects of treatments were evidenced by a dose-dependent induction of plasma hepatic vitellogenin titers. It can be concluded that low doses of estrogens, and possibly of xenoestrogens, may increase endocannabinoid signaling pathways.